Laser diode array, method of manufacturing the same, printer, and optical communication device

ABSTRACT

A method of manufacturing a laser diode array capable of inhibiting electric cross talk is provided. The method of manufacturing a laser diode array includes a processing step of forming a peel layer containing an oxidizable material and a vertical resonator structure over a first substrate sequentially from the first substrate side by crystal growth, and then selectively etching the peel layer and the vertical resonator structure to the first substrate, thereby processing into a columnar shape, a peeling step of oxidizing the peel layer from a side face, and then peeling the vertical resonator structure of columnar shape from the first substrate, and a rearrangement step of jointing a plurality of vertical resonator structures of columnar shape obtained by the peeling step to a surface of a metal layer of a second substrate formed with the metal layer on the surface.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a Continuation Application of patent applicationSer. No. 14/605,715 filed Jan. 26, 2015, to be issued on Jul. 5, 2016 asPat. No. RE46059, which is a Reissue Application of patent applicationSer. No. 13/064,218 filed Mar. 11, 2011, now U.S. Pat. No. 8,363,689issued on Jan. 29, 2013, which is a Continuation Application of Ser. No.12/219,491 filed Jul. 23, 2008, now U.S. Pat. No. 7,960,195 issued onJun. 14, 2011, which claims priority to Japanese Priority PatentApplication JP 2007-216401, filed in the Japan Patent Office on Aug. 22,2007, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a laser diode array including acolumnar vertical resonator structure, a method of manufacturing thesame, a printer including the laser diode array, and an opticalcommunication device including the laser diode array.

2. Description of the Related Art

In recent years, in the field of a laser diode (LD), a laser array inwhich a plurality of Vertical Cavity Surface Emitting Lasers (VCSEL) areformed on the same substrate has been actively developed. The laserarray is used as a light source for an optical communication device, alaser printer and the like.

In the field of the optical communication device, the laser printer andthe like, in the light of downsizing, it has been desired to propagatelaser light emitted from each laser diode formed on the same substrateby a single optical system. However, when the distance between eachlaser diode is reduced, cross talk due to heat generated from each laserdiode and a current leaked from each laser diode becomes significant. Asa result, interference, color blur and the like occur.

Therefore, for example, in Japanese Unexamined Patent ApplicationPublication No. 11-274633, a technique that a groove is provided betweeneach laser diode and a terminal section is provided on the both ends ofthe groove has been proposed. In the application, the following isrepresented. That is, a path to conduct generated heat to a region otherthan an adjacent laser diode is secured, in addition to that a heatconduction path to the adjacent laser diode is blocked. Accordingly,thermal cross talk is decreased without deterioration of thecharacteristics of each laser diode.

SUMMARY OF THE INVENTION

However, in the technique of Japanese Unexamined Patent ApplicationPublication No. 11-274633, it is difficult to increase the width and thedepth of the groove so much, and thus laser diodes adjacent to eachother are not able to be totally separated electrically. Therefore,there is an issue that electric cross talk occurs.

In view of the foregoing, in the invention, it is desirable to provide alaser diode array capable of inhibiting the electric cross talk, amethod of manufacturing the same, a printer including the laser diodearray, and an optical communication device including the laser diodearray.

According to an embodiment of the invention, there is provided a methodof manufacturing a laser diode array including the following respectivesteps A1 to A3:

Step A1: a processing step of forming a peel layer containing anoxidizable material and a vertical resonator structure over a firstsubstrate sequentially from the first substrate side by crystal growth,and then selectively etching the peel layer and the vertical resonatorstructure to the first substrate, thereby processing into a columnarshape;Step A2: a peeling step of oxidizing the peel layer from a side face,and then peeling the vertical resonator structure of columnar shape fromthe first substrate; andStep A3: a rearrangement step of jointing a plurality of verticalresonator structures of columnar shape obtained by the peeling step to asurface of a metal layer of a second substrate formed with the metallayer on a surface.

In the method of manufacturing a laser diode array according to theembodiment of the invention, the peel layer provided between the firstsubstrate and the vertical resonator structure is oxidized from the sideface. Thereby, a stress due to oxidation is generated in the peel layer.Thus, by applying an external force to the peel layer, the verticalresonator structure is easily peeled from the first substrate. Afterthat, the plurality of columnar vertical resonator structures obtainedby the peeling step are jointed to the surface of the metal layer of thesecond substrate. Thereby, a resistance component of the first substratethat is connected in series to each vertical resonator structure isseparated from each vertical resonator structure.

According to an embodiment of the invention, there is provided a laserdiode array including a first substrate in which a metal layer is formedon a surface thereof and a plurality of vertical resonator structures ofcolumnar shape. The respective vertical resonator structures are jointedto a surface of the metal layer. According to embodiments of theinvention, there are provided a printer and an optical communicationdevice using the foregoing laser diode array as a light source.

In the laser diode array, the printer, and the optical communicationdevice according to the embodiments of the invention, the respectivevertical resonator structures are jointed to the surface of the metallayer. Therefore, a resistance component of the common substrate that isconnected in series to each vertical resonator structure (commonsubstrate used for forming each vertical resonator structure) isseparated from each vertical resonator structure.

According to the method of manufacturing a laser diode array of theembodiment of the invention, the plurality of columnar verticalresonator structures peeled from the first substrate with the use ofoxidation of the peel layer are jointed to the surface of the metallayer of the second substrate. Thus, the resistance component of thefirst substrate that is connected in series to each vertical resonatorstructure is separated from each vertical resonator structure. Thereby,electric cross talk generated when the plurality of vertical resonatorstructures are formed on the common substrate is inhibited from beinggenerated.

According to the laser diode array, the printer, and the opticalcommunication device of the embodiments of the invention, the respectivevertical resonator structures are jointed to the surface of the metallayer. Therefore, the resistance component of the common substrate thatis connected in series to each vertical resonator structure is separatedfrom each vertical resonator structure. Thereby, electric cross talkgenerated when the plurality of vertical resonator structures are formedon the common substrate is inhibited from being generated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a laser diode array according to an embodimentof the invention;

FIG. 2 is a cross section view taken along arrows A-A of the laser diodearray of FIG. 1;

FIGS. 3A and 3B are cross section views for explaining an example of amethod of manufacturing the laser diode array of FIG. 1;

FIGS. 4A and 4B are cross section views for explaining steps followingFIGS. 3A and 3B;

FIG. 5 is a top view for explaining a step following FIGS. 4A and 4B;

FIG. 6 is a cross section view taken along arrows A-A of FIG. 5;

FIG. 7 is an equivalent circuit diagram of the laser diode array of FIG.1;

FIGS. 8A and 8B are waveform charts of a CW waveform and a pulsewaveform inputted to the laser diode array of FIG. 1;

FIGS. 9A and 9B are cross section views for explaining another exampleof a method of manufacturing the laser diode array of FIG. 1;

FIGS. 10A and 10B are cross section views for explaining steps followingFIGS. 9A and 9B;

FIGS. 11A and 11B are cross section views for explaining steps followingFIGS. 10A and 10B;

FIGS. 12A and 12B are cross section views for explaining steps followingFIGS. 11A and 11B;

FIG. 13 is a top view of a modification of the laser diode array of FIG.1;

FIG. 14 is a cross section view taken along arrows A-A of the laserdiode array of FIG. 13;

FIG. 15 is a schematic structural view of a printer according to anapplication example;

FIG. 16 is a schematic structural view of an optical communicationdevice according to another application example;

FIG. 17 is a cross section view of a laser diode array of a related art;

FIG. 18 is an equivalent circuit diagram of the laser diode array ofFIG. 11; and

FIGS. 19A and 19B are waveform charts for explaining cross talk in thelaser diode array of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Descriptions will be given of an embodiment of the invention in detailwith reference to the drawings.

FIG. 1 shows a top view of a laser diode array 1 according to anembodiment of the invention. FIG. 2 shows a cross sectionalconfiguration taken along arrows A-A of the laser diode array 1 ofFIG. 1. FIG. 1 and FIG. 2 schematically show the laser diode array 1,and the dimensions and the shapes in the figures are different fromthose used actually.

The laser diode array 1 includes a plurality of Vertical Cavity SurfaceEmitting Laser (VCSEL) devices 20 (vertical resonator structure) on asupport substrate 10. The laser diode array 1 has a function toconcurrently output a plurality of laser lights having the samewavelength.

Further, in the laser diode array 1, the plurality of laser diodedevices 20 are arranged on the surface on a metal layer 14 (describedlater) side of the support substrate 10, so that distance P between eachoptical axis AX of each laser light emitted from each laser diode device20 is short as much as possible. For example, as shown in FIG. 1, therespective laser diode devices 20 are arranged in a lattice pattern atalmost even intervals. However, the laser diode devices 20 are notnecessarily arranged in a vertical and reticular pattern at almost evenintervals, but may be, for example, arranged in a line at almost evenintervals.

Support Substrate 10

The support substrate 10 has, for example, a support base 11, aninsulating layer 12, an adhesive layer 13, the metal layer 14, a via 15(connection part), and an electrode layer 16. The insulating layer 12,the adhesive layer 13, and the metal layer 14 are layered in this orderfrom the support base 11 side on one face side of the support base 11.The electrode layer 16 is formed on the other face side of the one faceof the support base 11. The via 15 is formed to penetrate through thesupport base 11, the insulating layer 12, and the adhesive layer 13. Oneend thereof is in contact with the lower face of the metal layer 14, andthe other end thereof is in contact with the top face of the electrodelayer 16.

The support base 11 is made of a material different from that of thelaser diode device 20. The support base 11 is made of, for example, asilicon substrate. The insulating layer 12 is made of an insulativematerial such as silicon oxide (SiO₂) and silicon nitride (SiN). Theadhesive layer 13 is made of, for example multicrystalline silicon,amorphous silicon or the like. The multicrystalline silicon and theamorphous silicon have high affinity with the insulative material suchas silicon oxide (SiO₂) and silicon nitride (SiN). Thus, when theinsulative material such as silicon oxide (SiO₂) and silicon nitride(SiN) is used as the insulating layer 12 and the multicrystallinesilicon or the amorphous silicon is used as the adhesive layer 13, thecontact characteristics between the insulating layer 12 and the adhesivelayer 13 become strong.

Laser Diode Device 20

The laser diode device 20 is joined to the metal layer 14 of the supportsubstrate 10. The laser diode device 20 has a columnar verticalresonator structure in which, for example, a lower contact layer 21, alower DBR layer 22, a lower spacer layer 23, an active layer 24, anupper spacer layer 25, a current confinement layer 26, an upper DBRlayer 27, and an upper contact layer 28 are layered in this order fromthe metal layer 14 side. That is, the laser diode device 20 is obtainedby removing a separately prepared semiconductor substrate 40 (describedlater) from a structure in which the foregoing vertical resonatorstructure is formed by crystal growth on the semiconductor substrate 40.

The lower contact layer 21 is made of, for example, n-typeAl_(x1)Ga_(1-x1)As (0≦x1<1). The lower DBR layer 22 is formed byalternately layering a low refractive index layer (not shown) and a highrefractive index layer (not shown). The low refractive index layer ismade of, for example, n-type Al_(x2)Ga_(1-x2)As (0<x2<1) having anoptical thickness of λ₁/4 (λ₁ is an oscillation wavelength). The highrefractive index layer is made of, for example, n-typeAl_(x3)Ga_(1-x3)As (0≦x3<x2) having an optical thickness of λ₁/4. Thelower spacer layer 23 is made of, for example, n-type Al_(x4)Ga_(1-x4)As(0≦x4<2). The lower contact layer 21, the lower DBR layer 22, and thelower spacer layer 23 contain an n-type impurity such as silicon (Si).

The active layer 24 has a multi-quantum well structure in which a welllayer (not shown) made of undoped In_(x5)Ga_(1-x5)As (0<x5<1) and abarrier layer (not shown) made of undoped In_(x6)Ga_(1-x6)N (0<x6<x5)are alternately layered. Of the active layer 24, the region opposed to acurrent injection region 26A (described later) is a light emittingregion 24A.

The upper spacer layer 25 is made of, for example, p-typeAl_(x7)Ga_(1-x7)As (0≦x7<1). The upper DBR layer 27 is formed byalternately layering a low refractive index layer (not shown) and a highrefractive index layer (not shown). The low refractive index layer ismade of, for example, p-type Al_(x8)Ga_(1-x8)As (0<x8<1) having anoptical thickness of λ₁/4. The high refractive index layer is made of,for example, p-type Al_(x9)Ga_(1-x9)N (0≦x9<x8) having an opticalthickness of λ₁/4. The upper contact layer 28 is made of, for example,p-type Al_(x10)Ga_(1-x10)N (0≦x10<1). The upper spacer layer 25, theupper DBR layer 27, and the upper contact layer 28 include a p-typeimpurity such as magnesium (Mg).

The current confinement layer 26 has a current confinement region 26B inthe peripheral region of a current injection region 26A.

The current injection region 26A is made of, for example, p-typeAl_(x11)Ga_(1-x11)As (0<x11≦1). The current injection region 26A ispreferably made of a material having an oxidation rate equal to orslower than that of a peel layer 41D described later.

For example, when the peel layer 41D is made of AlAs, the currentinjection region 26A is made of Al_(x11)Ga_(1-x11)As (0.98≦x11≦1). Inthe case where the current injection region 26A is made of AlAs (x11=1),the thickness of the current injection region 26A needs to be smallerthan the thickness of the peel layer 41D. Meanwhile, when the currentinjection region 26A is made of Al_(x11)Ga_(1-x11)As (0.98≦x11<1), thethickness of the current injection region 26A may be equal to or smallerthan the thickness of the peel layer 41D. However, as will be describedlater, when oxidation step of the peel layer 41D is performed separatelyfrom oxidation step of the current confinement layer 26D, the materialof the current injection region 26A is not particularly limited inrelation to the peel layer 41D.

Meanwhile, the current confinement region 26B contains, for example,Al₂O₃ (aluminum oxide). As will be described later, the currentconfinement region 26B is obtained by oxidizing concentrated Alcontained in a current confinement layer 26D from the side face.Therefore, the current confinement layer 26 has a function to confine acurrent.

In the laser diode device 20 of this embodiment, a circular electrodelayer 30 is formed on the top face of the upper contact layer 28. Theelectrode layer 30 is formed by layering, for example, a Ti layer, a Ptlayer, and an Au layer in this order. The electrode layer 30 iselectrically connected to the upper contact layer 28.

Further, an insulating film 31 is formed over the entire surfaceincluding each laser diode device 20 and the electrode layer 30. Theinsulating film 31 is made of an insulative material such as siliconoxide (SiO₂) and silicon nitride (SiN). An aperture is formed in part ofthe region opposed to the electrode layer 30 of the insulating film 31.An electrode pad 33 electrically connected to a wiring layer 32 throughthe aperture is formed on the surface of the insulating film 31 (referto FIG. 1).

The laser diode array 1 having the foregoing configuration may bemanufactured as follows, for example.

First, the laser diode device 20 is manufactured. For example, in thecase where the vertical resonator structure is formed from GaAs-basedGroup III-V compound semiconductor, for example, the vertical resonatorstructure is formed by Metal Organic Chemical Vapor Deposition (MOCVD)method with the use of TMA (trimethyl aluminum), TMG (trimethylgallium), TMIn (trimethyl indium), or AsH₃ (arsine) as a raw materialgas.

The GaAs-based Group III-V compound semiconductor represents asemiconductor that contains at least Ga out of Group 3B elements in theshort period periodic table and at least As (arsenic) out of Group 5Belements in the short period periodic table.

Specifically, the peel layer 41D, the lower contact layer 21, the lowerDBR layer 22, the lower spacer layer 23, the active layer 24, the upperspacer layer 25, the current confinement layer 26D (layer to beoxidized), the upper DBR layer 27, and the upper contact layer 28 arelayered in this order over the semiconductor substrate 40 (GaAssubstrate) (FIG. 3A).

The foregoing current confinement layer 26D is made of the same materialas that of the current injection region 26A, and will become the currentconfinement layer 26 by the after-mentioned oxidation treatment. Thepeel layer 41D is preferably structured to have a faster oxidation ratein the lamination in-plane direction than that of the currentconfinement layer 26D.

For example, in the case where the current confinement layer 26D is madeof the same material as that of the peel layer 41D (for example,Al_(x11)Ga_(1-x11)As (0.98<x11≦1), the thickness of the peel layer 41Dis preferably larger than that of the current confinement layer 26D. Inthe case where the current confinement layer 26D is made ofAl_(x11)Ga_(1-x11)As (0.98<x11<1), the peel layer 41D is preferably madeof AlAs. In the case where the current confinement layer 26D is made ofAl_(x11)Ga_(1-x11)As (0.98<x11<1) and the peel layer 41D is made ofAlAs, that is, when the peel layer 41D is made of a material having afaster oxidation rate than that of the current confinement layer 26D,the thickness of the peel layer 41D may be equal to or larger than thethickness of the current confinement layer 26D.

Next, a region from the upper contact layer 28 to part of thesemiconductor substrate 40 is selectively etched by, for example, dryetching method to form a mesa shape (FIG. 3B). Thereby, the peel layer41D is exposed on the side face of a mesa M.

Next, heat treatment is performed at high temperature in the water vaporatmosphere, and the current confinement layer 26D and the peel layer 41Dare concurrently oxidized from the side face of the mesa M. Theoxidation treatment is performed until almost all of the peel layer 41Dis oxidized and the diameter of the non-oxidized region of the currentconfinement layer 26D becomes a desired value. Thereby almost all of thepeel layer 41D becomes an insulating layer (aluminum oxide), and anoxidized peel layer 41 is formed (FIG. 4A). Further, since the outeredge region of the current confinement layer 26D becomes an insulatinglayer (aluminum oxide), the current confinement region 26B is formed inthe outer edge region, and the current injection region 26A is formed inthe central region thereof. Accordingly, the laser diode device 20 isformed over the semiconductor substrate 40 (FIG. 4A).

Next, for example, the laser diode device 20 is peeled from thesemiconductor substrate 40 by, for example, vacuum contact or by using alight curable adhesive sheet or the like (FIG. 4B). Out of interfacesbetween each layer composing the laser diode device 20, at the interfacebetween the oxidized peel layer 41 and the lower contact layer 21, theoxidized peel layer 41 and the lower contact layer 21 are not contactedwith each other in a graded manner. That is, at the interface betweenthe oxidized peel layer 41 and the lower contact layer 21, an interlayerin which the both materials are mixed with each other does not exist.Otherwise, even if such an interlayer exists, the interlayer slightlyexists to the degree that the interlayer is ignorable compared to thethickness of interlayer at the other interfaces. Thus, since a stresscaused by oxidation has been applied to the interface between theoxidized peel layer 41 and the lower contact layer 21. The laser diodedevice 20 is able to be relatively easily peeled at the interfacebetween the oxidized peel layer 41 and the lower contact layer 21 or inthe vicinity thereof by the peeling step.

Heating (alloying) may be performed at about from 300 deg C. to 400 degC. before the peeling step. In this case, the stress at the interfacebetween the oxidized peel layer 41 and the lower contact layer 21 isfurther increased, and thus the laser diode device 20 is able to beeasily peeled. If the oxidized peel layer 41 remains on the laser diodedevice 20 side, the portion of the oxidized peel layer 41 remaining onthe laser diode device 20 side is removed by wet etching.

Next, the plurality of laser diode devices 20 are arranged with thelower contact layer 21 side downward on the metal layer 14 of thesupport substrate 10, and are jointed to the metal layer 14 (FIG. 5 andFIG. 6). FIG. 6 is a cross sectional configuration view taken alongarrows A-A of FIG. 5.

Next, the circular electrode layer 30 is formed on the top face of thelaser diode device 20 (FIG. 2). Subsequently, the insulating film 31 isformed over the entire surface including the laser diode device 20 andthe electrode layer 30. After that, the electrode pad 33 is formed in aplace with a given distance from the laser diode 20 in the surface ofthe insulating film 31. After that, the aperture (not shown) is formedin part of the region opposed to the electrode layer 30 in theinsulating film 31. After that, the wiring layer 32 extending from thesurface of the electrode layer 30 exposed in the aperture to theelectrode pad 33 is formed. Accordingly, the laser diode array 1 of thisembodiment is manufactured.

In the laser diode array 1 of this embodiment, when a given voltage isapplied between the connection pad 33 electrically connected to theelectrode layer 30 on each laser diode device 20 and the electrode layer16, a current is injected into the active layer 24, light emission isgenerated by electron-hole recombination, and stimulated emission isrepeated in the device. As a result, laser oscillation is generated in agiven wavelength λ₁, laser light in wavelength λ₁ is outputted outsidefrom the light emitting region 24A of each laser diode device 20 throughthe aperture of the electrode layer 30.

In f a laser diode array 100 of the related art shown in FIG. 17, thatis, in the laser array in which a columnar VCSEL 120 obtained bylayering, for example, a lower DBR layer 121, a lower spacer layer 122,an active layer 123, an upper spacer layer 124, a current confinementlayer 125 (current injection region 125A and a current confinementregion 125B), an upper DBR layer 126, and an upper contact layer 127 inthis order over a common substrate 110 is directly formed by crystalgrowth, as shown in the equivalent circuit shown in FIG. 18, resistancecomponent R3 exists between each laser diode 120 and ground GNDindependently of a current path of other laser diode 120, and resistancecomponent R4 exists on the current path common to each laser diode 120.

The resistance component R4 is a resistance component of the commonsubstrate 110. In the case where the resistance component R4 exists, forexample, when one laser diode device 120 is CW-driven as shown in FIG.8A and another laser diode device 120 adjacent to the foregoing onelaser diode device 120 is pulse-driven as shown in FIG. 8B, in theequivalent circuit of FIG. 18, input voltage V_(L1) of the CW-drivenlaser diode device 120 has a wavy waveform including noise as shown inFIG. 19A, and input voltage V_(L2) of the pulse-driven laser diodedevice 120 has a distorted rectangular waveform including noise as shownin FIG. 19B. That is, electric cross talk is generated between the laserdiode devices 120 adjacent to each other.

Meanwhile, in this embodiment, each laser diode device 20 is jointed tothe surface of the metal layer 14 of the support substrate 10. Thus, asshown in FIG. 7, in the equivalent circuit of the laser diode array 1,the resistance component R3 exists between each laser diode device 20and the ground GND independently of a current path of other laser diodedevice 20, but no resistance component exists on the current path commonto each laser diode device 20. This is because in the manufacturingcourse of this embodiment, the semiconductor substrate 40 is removed(peeled) from the structure in which the vertical resonator structure isformed by crystal growth over the semiconductor substrate 40, andthereby the resistance component of the semiconductor substrate 40 thatis connected in series to each vertical resonator structure is separatedfrom each vertical resonator structure.

Thereby, for example, in the case where one laser diode device 20 isCW-driven as shown in FIG. 8A and another laser diode device 20 adjacentto the foregoing one laser diode device 20 is pulse-driven as shown inFIG. 8B, in the equivalent circuit of FIG. 7, the input voltage V_(L1)of the CW-driven laser diode device 20 has a flat waveform not includingnoise as an input voltage waveform, and the input voltage V_(L2) of thepulse-driven laser diode device 20 has a rectangular waveform notincluding noise as the input voltage waveform. That is, electric crosstalk is not generated between the laser diode devices 20 adjacent toeach other.

As described above, in this embodiment, since each laser diode device 20is jointed to the surface of the metal layer 14 of the support substrate10, the resistance component of the semiconductor substrate 40 that isconnected in series to each laser diode device 20 is separated from eachlaser diode device 20. Thereby, electric cross talk between the laserdiode devices 20 adjacent to each other is inhibited from beinggenerated.

Modification

In the foregoing embodiment, the oxidation steps of the peel layer 41Dand the current confinement layer 26D are concurrently performed.However, each oxidation step may be performed separately. For example,it is possible that after the side face of the current confinement layer26D is coated with a protective film so that the side face of the peellayer 41D is not coated therewith, the oxidized peel layer 41 is formedby oxidizing the peel layer 41D from the side face, the protective filmis removed, and then the current confinement layer 26D is oxidized fromthe side face to form the current confinement layer 26.

Further, the formation step of the laser diode device 20 may beperformed, for example, as follows. First, the peel layer 41D, the lowercontact layer 21, the lower DBR layer 22, the lower spacer layer 23, theactive layer 24, the upper spacer layer 25, the current confinementlayer 26D (layer to be oxidized), the upper DBR layer 27, and the uppercontact layer 28 are layered in this order over the semiconductorsubstrate 40 (GaAs substrate) (FIG. 3A). Then, a region from the uppercontact layer 28 to part of the lower DBR layer 22 is selectively etchedby, for example, dry etching method to form a mesa shape.

Next, heat treatment is performed at high temperature in the water vaporatmosphere, the current confinement layer 26D is oxidized from the sideface of the mesa M to form the current confinement layer 26 (FIG. 9B).Since the peel layer 41D is not exposed on the side face of the mesa M,the peel layer 41D is not oxidized.

Next, a protective film 19 is formed on the entire surface including themesa M (FIG. 10A). After that, a groove 29A penetrating thorough theprotective film 19 is formed to surround the mesa M (FIG. 10B). Thereby,the lower DBR layer 22 is exposed on the bottom face of the groove 29A.

Next, for example, the lower DBR layer 22 and the lower contact layer 21that are directly under the groove 29A are selectively removed by using,for example, a phosphoric acid etchant (FIG. 11A). After that, the peellayer 41D is selectively removed by using a fluorinated acid etchant(FIG. 11B). Thereby, the contact force by the peel layer 41D between thesemiconductor substrate 40 and the lower DBR layer 22 is lowered.

Next, a support substrate 42 is bonded to the top face of the protectivefilm 19 (FIG. 12A). After that, by using the support substrate 42, thelaser diode device 20 is peeled from the semiconductor substrate 40(FIG. 12B). Accordingly, the laser diode device 20 is able to be formedas well.

In the foregoing embodiment, the VCSEL 20 is jointed to the surface ofthe metal layer 14 of the support substrate 10 having the via 15.However, for example, as shown in FIG. 13 and FIG. 14, it is possiblethat a support substrate 50 in which the insulating layer 12, theadhesive layer 13, and the metal layer 14 are sequentially layered fromthe support base 11 side is prepared on one surface of the support base11, and the VCSEL 20 is jointed to the surface of the metal layer 14 ofthe support substrate 50. However, in this case, for example, it isnecessary that an aperture 31A is formed in part of the insulating layer31 formed on the surface of the metal layer 14, part of the metal layer14 is exposed from the aperture, and the exposed section is used as anelectrode pad 14A to decrease the potential of the metal layer 14 to theground potential.

Further, in the foregoing embodiment, the wiring layer 32 and theelectrode pad 33 are formed over the support substrate 10 with theinsulating layer 31 in between. However, for example, it is possiblethat a buried layer made of an insulative material such as polyimide isprovided around the laser diode device 20, the wiring layer 32 and theelectrode pad 33 are formed on the top face of the buried layer, andthereby the capacity component generated between the wiring layer 32/theelectrode pad 33 and the metal layer 14 is decreased as much aspossible.

Application Example

The laser diode array 1 according to the foregoing embodiment or themodification thereof is suitably applicable to, for example, a printersuch as a laser printer and an optical communication device such as amultichannel optical integrated device. For example, as shown in FIG.15, as a light source 61 in a laser printer 60 including the lightsource 61, a polygon mirror 62 for reflecting light from the lightsource 61 and scanning the reflected light, a fθ lens 63 for guiding thelight from the polygon mirror 62 to a photoconductive drum 64, thephotoconductive drum 64 receiving the light from the fθ lens 63 to forman electrostatic latent image, and a toner supplier (not shown) adheringthe toner according to the electrostatic latent image to thephotoconductive drum 64, the laser diode array 1 may be used. Further,for example, as shown in FIG. 16, as a light source 72 in an opticalcommunication device 70 including the light source 72, a light guide 73in which a light input end is arranged correspondingly to a light outputend of the light source 72, and an optical fiber 74 in which a lightinput end is provided correspondingly to a light output end of the lightguide 73 on a support substrate 71, the laser diode array 1 may be used.

While the descriptions have been hereinbefore given of the inventionwith reference to the embodiment and the like, the invention is notlimited to the foregoing embodiment and the like, and variousmodifications may be made.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alternations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A laser diode array comprising: a supportsubstrate including a support base, a first insulating layer, anadhesive layer, a metal layer, and a second insulating layer; and aplurality of vertical resonator structures, each having columnar shapeand electrically connected to the metal layer, where each of thevertical resonator structures includes a first contact layer directlyconnected to the metal layer, a first DBR layer, a first spacer layer,an active layer, a second spacer layer, a second DBR layer, and a secondcontact layer sequentially from the metal layer side; wherein anaperture is formed in a second insulating layer so as to expose aportion of the metal layer, and wherein the second insulating layer isformed over said each of the vertical resonator structures.
 2. Anoptical communication module comprising: the laser diode array accordingto claim
 1. 3. The optical communication module according to claim 2,further comprising: a waveguide member optically coupled to the laserdiode array.
 4. The laser diode array according to claim 1, wherein saideach of the vertical resonator structures is discretely formed from thesupport substrate and jointed to the support substrate.
 5. The laserdiode array according to claim 1, wherein said each of the verticalresonator structures is made of a material different from a material ofthe support substrate.
 6. The laser diode array according to claim 1,wherein in the support substrate, one or a plurality of connection partsthat penetrate a portion other than the metal layer in the supportsubstrate are formed to be in contact with the metal layer.
 7. A printercomprising the laser diode array of claim
 1. 8. The laser diode arrayaccording to claim 1, wherein said each of the vertical resonatorstructures further includes a current confinement layer formed betweenthe second spacer layer and the second DBR layer.
 9. The laser diodearray according to claim 1, wherein the current confinement layerincludes a current confinement region that is in a peripheral region ofa current injection region.